Ex Vivo Confocal Microscopy: Revolution in Fast Pathology in Dermatology

J. Malvehy; J. Pérez-Anker; A. Toll; R. Pigem; A. Garcia; L.L. Alos; S. Puig


The British Journal of Dermatology. 2020;183(6):1011-1025. 

In This Article

Abstract and Introduction


Confocal microscopy with in vivo and ex vivo modalities has been used in the evaluation of skin cancer and other dermatological disorders. Recent developments in ex vivo confocal microscopy allow for faster pathology assessment with greater accuracy by the visualization of cellular and architectural details, similarly to standard pathology, in either paraffin-embedded or frozen samples. They include the possibility of multimodal confocal microscopy using different lasers and fusion images. New staining protocols including immunostaining, with no damage to conventional histopathology preparation, have been recently described in melanocytic tumours and inflammatory skin diseases. Digital staining with haematoxylin and eosin is also incorporated in the new devices. In this review the applications of ex vivo confocal microscopy will be presented with the description of the technique and the technology, clinical evidence in dermatology and other fields, and further applications.


In the last decade a revolution in dermatology has been produced with the introduction of confocal microscopy (CM). This is an optical method that in a few seconds can provide high-resolution images of in vivo tissue or fresh, nonfixed, thick pieces of specimens, which are optically scanned in slices, instead of using a microtome blade. Two different confocal imaging systems are currently available: (i) reflectance confocal microscopy (RCM), using the refractive properties of subcellular structures, and (ii) fluorescence confocal microscopy (FCM), using fluorochromes to increase the cell-to-stroma contrast. RCM with no contrast agents has been used mainly for in vivo accessible tissue examination in three main fields: the examination of retina and cornea,[1–3] neoplastic and inflammatory skin diseases,[4] and the exploration of body cavities reachable through probe-based confocal laser endomicroscopes.[5–10]

Ex vivo CM has attracted the attention of dermatologists and Mohs surgeons in skin cancer, and also in other tumours including breast cancer, prostate cancer, nephrological tumours and central nervous system tumours. In dermatology, ex vivo CM has been applied mainly to surgical oncology and in particular to skin carcinoma for fast assessment of tumour margins during surgery in basal cell carcinoma (BCC), squamous cell carcinoma (SCC), dermatofibrosarcoma and some adnexal tumours. In high-risk tumours with frequent relapses after surgery, three-dimensional pathological evaluation (e.g. Mohs micrographic surgery, slow-Mohs) is recommended in international guidelines to ensure free margins for the management of skin cancer.[11–13] Unfortunately, the availability of this procedure is limited in Europe due to the lack of reimbursement, the low number of dedicated units, and the elevated cost and time consumed with the procedure in busy referral hospitals, which are frequently overloaded with skin cancer interventions. Ex vivo CM can be seen as a technical solution due to the easy-to-use and faster methodology, which reduces the cost and surgical time.